This invention relates to a new measure of diastolic pressure. It provides a method and apparatus for diastolic pressure measurement characterized by accuracy, operator ease, and little patient discomfort. Further, the invention can be practiced with a variety of instrument configurations.
The accurate measurement of blood pressure is an important tool in preventive and recuperative cardiac care. The common sphygmomanometer employing a manually inflated pressure cuff and mercury manometer is accordingly well known. It is used with a stethoscope, with which the medical professional listens for different acoustic pulses, termed Korotkoff sounds.
The prior art regarding the accurate measurement of blood pressure also includes the disclosures in the following U.S. Pat. Nos. 3,527,197; 3,552,381; 3,903,872; 3,905,354; 3,939,824; 4,009,709; 4,058,117; and 4,074,711. Problems with these and other prior sphygmomanometers include operator difficulty in perceiving important changes in Korotkoff sounds and in distinguishing Korotkoff sounds from motion artifacts and other background noise. Also, the common sphygmomanometer first occludes the subject's artery to measure systolic pressure, which can cause sufficient discomfort so that the subsequent measurement of diastolic pressure is not accurate. Electronic techniques for measuring blood pressure also have shortcomings stemming from the difficulty in detecting and identifying pressure pulses properly. These problems are particularly persistent in measuring diastolic pressure, rather than in measuring more readily discernible systolic value.
It is accordingly an object of this invention to provide an improved method and apparatus for measuring diastolic pressure. More particularly, it is an object to provide a diastolic pressure measuring method and apparatus free of problems heretofore encountered in distinguishing Korotkoff sounds of interest from other signals. Accordingly, the objects of the invention include providing such a method and apparatus which are accurate and easy to use without error.
It is a further object of the invention to provide a method and apparatus for the non-intrusive measurement of diastolic pressure which subjects the patient to little discomfort, and which can readily be automated.
It is also an object of the invention to provide a diastolic pressure measuring method and apparatus which can readily be practiced without requiring sound perception by the operator. This both avoids a potential source of error and overcomes one possible source of concern for the patient, as contrasted with prior devices which require the operator to listen carefully for significant sound characteristics.
Other objects of the invention will in part be obvious and will in part appear hereinafter.